Exposure apparatus and method of manufacturing display device using the same

ABSTRACT

Provided are an exposure apparatus including a light source unit which provides light for exposure and comprises micro light emitting diodes arranged in a matrix form; a substrate transfer unit which transfers a target substrate; and a control unit which controls at least one of the light source unit and the substrate transfer unit. The control unit allocates coordinates or an address to each micro light emitting diode and individually controls an amount of light of each micro light emitting diode according to a preset pattern based on the coordinates or the address.

This application claims the benefit of Korean Patent Application No.10-2020-0045791, filed on Apr. 16, 2020, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference in its entirety.

BACKGROUND 1. Field

The present disclosure relates to an exposure apparatus and a method ofmanufacturing a display device using the same.

2. Description of the Related Art

A photolithography device is a device that forms complicated circuitpatterns using light, like photo printing technology. Thephotolithography device may be used in pattern forming formanufacturing, for example, semiconductor devices, display panels suchas liquid crystal displays (LCDs), plasma display panels (PDPs) andelectroluminescent displays (ELDs), integrated circuits, and flat paneldisplays.

In conventional photolithography, a desired pattern is formed on asubstrate coated with a photoresist by exposing the photoresist to lightthrough a photomask in which a pattern is formed of a metal thin film,e.g., mainly chromium, on a quartz or glass plate.

In the above process, a patterning device composed of an array ofindividually operable elements may be used instead of the photomask. Thepatterning device is programmed to form a beam of a desired patternusing the array of the individually operable elements. This “maskless”system can form patterns of various shapes at no additional cost becausea beam radiated through the program can be modified into a desiredpattern. In addition, the maskless system is faster and cheaper than aconventional mask-based system.

A representative programmable patterning device is an exposure apparatususing a digital minor device (DMD). The DMD is a device used as anelement for generating images in electronic products such as projectorsand televisions and is a key component for generating patterns in amaskless lithography system. In the DMD, a minor rotates according to anelectrical signal to form an image of a desired pattern. That is, theDMD is like a photomask capable of pattern modification. An exposureapparatus using the DMD allows easy use of previous data when its designis changed, can be immediately corrected for design errors, and canreduce design time. On the other hand, the DMD requires a complicatedoptical system for patterning image projection and suffers from lightloss because light is irradiated through the DMD.

SUMMARY

Aspects of the present disclosure provide an exposure apparatus whichcan form various patterns without replacement of a light source or amask and a method of manufacturing a display device using the exposureapparatus.

Aspects of the present disclosure also provide an exposure apparatuswith low light loss and a method of manufacturing a display device usingthe exposure apparatus.

Aspects of the present disclosure also provide an exposure apparatuswhich can save an installation space and a method of manufacturing adisplay device using the exposure apparatus.

However, aspects of the present disclosure are not restricted to theones set forth herein. The above and other aspects of the presentdisclosure will become more apparent to one of ordinary skill in the artto which the present disclosure pertains by referencing the detaileddescription of the present disclosure given below.

According to an aspect of the present disclosure, there is provided anexposure apparatus including a light source unit which provides lightfor exposure and comprises micro light emitting diodes arranged in amatrix form; a substrate transfer unit which transfers a targetsubstrate; and a control unit which controls at least one of the lightsource unit and the substrate transfer unit. The control unit allocatescoordinates or an address to each micro light emitting diode andindividually controls an amount of light of each micro light emittingdiode according to a preset pattern based on the coordinates or theaddress.

According to another aspect of the present disclosure, there is providedan exposure apparatus including a light source unit which provides lightfor exposure and comprises unit light emitting cells arranged in amatrix form; a substrate transfer unit which transfers a targetsubstrate; and a control unit which controls at least one of the lightsource unit and the substrate transfer unit. The control unit allocatescoordinates or an address to each unit light emitting cell andindividually controls an amount of light of each unit light emittingcell according to a preset pattern based on the coordinates or theaddress.

According to another aspect of the present disclosure, there is provideda method of manufacturing a display device including stacking at leastone material layer on a base substrate; coating a photosensitivematerial on the at least one material layer; outputting a preset patternby individually controlling an amount of light of each micro lightemitting diode; exposing the photosensitive material to light; removinga part of the photosensitive material; and etching a first pattern inthe at least one material layer.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings.

FIG. 1 is a perspective view of an exposure apparatus according to anembodiment.

FIG. 2 is a plan view of the exposure apparatus of FIG. 1 as viewed fromabove.

FIG. 3 is a plan view of a light source unit of FIG. 1 as viewed frombelow.

FIG. 4 is a cross-sectional view taken along line A-A′ of FIG. 3.

FIG. 5 illustrates an auxiliary optical system.

FIGS. 6, 7, 8, 9, 10, and 11 illustrate a method of controlling anexposure apparatus according to an embodiment of the present disclosure.

FIGS. 12, 13, and 14 illustrate a method of controlling an exposureapparatus according to an embodiment of the present disclosure.

FIGS. 15, 16, 17, 18, 19, and 20 illustrate a method of manufacturing adisplay device according to an embodiment of the present disclosure.

FIGS. 21, 22, 23, and 24 illustrate an exposure apparatus and a methodof manufacturing a display device using the same according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter withreference to the accompanying drawings, in which embodiments are shown.This inventive concept may, however, be embodied in different forms andshould not be construed as limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the inventiveconcept to those skilled in the art.

It will also be understood that when a layer is referred to as being“on” another layer or substrate, it can be directly on the other layeror substrate, or intervening layers may also be present. In contrast,when an element is referred to as being “directly on” another element,there are no intervening elements present.

Although the terms “first”, “second”, etc. may be used herein todescribe various elements, these elements should not be limited by theseterms. These terms may be used to distinguish one element from anotherelement. Thus, a first element discussed below may be termed a secondelement without departing from teachings of one or more exemplaryembodiments.

Hereinafter, specific embodiments will be described with reference tothe attached drawings.

FIG. 1 is a perspective view of an exposure apparatus 1 according to anembodiment. FIG. 2 is a plan view of the exposure apparatus 1 of FIG. 1as viewed from above. FIG. 3 is a plan view of a light source unit 100of FIG. 1 as viewed from below. FIG. 4 is a cross-sectional view takenalong line A-A′ of FIG. 3.

In embodiments, a first direction X, a second direction Y, and a thirddirection Z intersect each other in different directions. In thedrawings, a horizontal direction of the exposure apparatus 1 is definedas the first direction X, a vertical direction as the second directionY, and a height direction as the third direction Z. The third directionZ includes an upward direction toward an upper side in the drawings anda downward direction toward a lower side in the drawings. Accordingly, asurface of a member disposed to face the upward direction may bereferred to as an upper surface, and the other surface of the memberdisposed to face the downward direction may be referred to as a lowersurface. However, directions mentioned in the embodiments should beunderstood as relative directions.

The exposure apparatus 1 will be described below as, for example, amaskless photolithography apparatus that does not require an opticalmask in a photolithography process generally using photoresist. However,the exposure apparatus 1 may be any apparatus used in an exposure anddevelopment process for pattern formation.

Referring to FIGS. 1 through 4, the exposure apparatus 1 includes thelight source unit 100, a substrate transfer unit 200, and a control unit300. The exposure apparatus 1 may further include a sensing unit 400.

The light source unit 100 includes light emitting elements and isdisposed above the substrate transfer unit 200. The light source unit100 may project light downward toward a target substrate 10 loaded onthe substrate transfer unit 200.

The light source unit 100 may expose the target substrate 10 to light sothat a layer including photosensitive material PR is cured according toa specific pattern. The target substrate 10 refers to a substrateexposed to light by the exposure apparatus 1. In an embodiment, thetarget substrate 10 may include a base substrate 11, a material layer 12stacked on the base substrate 11, and a photosensitive material PRstacked on the material layer 12. The photosensitive material PRincludes a photoresist. For example, the photosensitive material PR maybe a photosensitive film formed by coating the photoresist on thematerial layer 12. The material layer 12 may be, for example, a materialfor forming thin-film transistors.

The light source unit 100 may be disposed to overlap the substratetransfer unit 200. Specifically, the substrate transfer unit 200 may bedisposed along the first direction X in which the target substrate 10 istransferred. The light source unit 100 may be disposed along the seconddirection Y intersecting the first direction X. The substrate transferunit 200 and the light source unit 100 may at least partially overlapeach other in the third direction Z. In an embodiment, a width of thelight source unit 100 in the second direction Y may be equal to orgreater than a width of the substrate transfer unit 200 in the seconddirection Y. Accordingly, during exposure, the exposure apparatus 1 mayform one pattern in a specific area of the target substrate 10 disposedbetween the light source unit 100 and the substrate transfer unit 200through one exposure.

The light source unit 100 may be spaced apart from the substratetransfer unit 200 by a predetermined distance. The predetermineddistance may vary according to a thickness of the target substrate 10.Specifically, in the exposure apparatus 1, the light source unit 100 maybe disposed close to the substrate transfer unit 200 or the targetsubstrate 10 as an optical system 140 to be described later isintegrated with the light source unit 100. Accordingly, an apparatus orsystem for lithography can be miniaturized, and light loss can beminimized. For example, during exposure, the distance between the lightsource unit 100 and the substrate transfer unit 200 in the thirddirection Z may be about 500 μm or less. For another example, duringexposure, a distance between the light source unit 100 and the targetsubstrate 10 in the third direction Z may be about 500 μm or less. Foranother example, during exposure, the distance between the light sourceunit 100 and the target substrate 10 in the third direction Z may beabout 5 μm or less. For another example, during exposure, the distancebetween the light source unit 100 and the target substrate 10 in thethird direction Z may be about 1 μm or more.

Accordingly, it is possible to prevent interference due to a differencein flatness between the light source unit 100 and the target substrate10 and prevent transfer of a material such as photoresist due to contactbetween them. In addition, when the light source unit 100 and the targetsubstrate 10 are in excessively close contact with each other, a darkportion may be formed on a part of the target substrate 10 by a lightblocking member 130 to be described later. For proper dispersion oflight, the light source unit 100 and the target substrate 10 may bespaced apart by a predetermined distance to prevent the formation of thedark portion. In some embodiments, the exposure apparatus 1 may becontrolled by the control unit 300 to be described later and may furtherinclude a light source moving unit which can move the light source unit100 in at least one of the first, second, and third directions X, Y, andZ for alignment of the light source unit 100.

The light source unit 100 may be disposed parallel to the targetsubstrate 10. In other words, the light source unit 100 may be disposedparallel to a transfer direction of the substrate transfer unit 200 oran upper surface of the substrate transfer unit 200. Accordingly, thelight source unit 100 may uniformly irradiate light to the target unit10. In an embodiment, the target substrate 10 may be transferred in thefirst direction X, and the light source unit 100 may be disposed along aplane parallel to the first direction X and the second direction Y. Insome embodiments, the light source unit 100 may be inclined to thetarget substrate 10 or a movement direction of the target substrate 10.In some embodiments, light of the light source unit 100 may becontrolled individually according to the inclination by the control unit300 to be described later.

The light source unit 100 may include unit light emitting cells LC. Theunit light emitting cells LC may respectively correspond to micro lightemitting diodes (LEDs) 120 of a micro LED array MLA to be describedlater. The light source unit 100 may be electrically connected to thecontrol unit 300 to be described later, and the unit light emittingcells LC may be individually controlled to be turned on or off by thecontrol unit 300. In some embodiments, the light source unit 100 mayfurther include a driver integrated circuit which transmits a drivingsignal to a micro LED 120 corresponding to each unit light emitting cellLC, and the driver integrated circuit may drive each micro LED 120individually based on a control signal received from the control unit300.

The light source unit 100 may include a light source unit substrate 110,the micro LED array MLA, and the optical system 140. The light sourceunit 100 may further include the light blocking member 130.

The light source unit substrate 110 is disposed parallel to the targetsubstrate 10 on the substrate transfer unit 200 and supports the bottomof the micro LED array MLA. In an embodiment, a thickness of the lightsource unit substrate 110 may be about 100 to 200 μm. Accordingly, thefirst light source substrate 110 may maximize space efficiency, increaselight transmittance of the light source, and have a minimum thicknessfor mounting a configuration such as a thin-film transistor to bedescribed later.

The light source unit substrate 110 may be made of a transparentmaterial to allow light emitted from the micro LEDs 120 to reach thetarget substrate 10 through the light source unit substrate 110. Thelight source unit substrate 110 may be made of a transparent insulatingmaterial such as sapphire, glass or polymer resin. In some embodiments,the light source unit substrate 110 may include layers made of atransparent conductive material, and the layers may include, forexample, a circuit such as a thin-film transistor structure forindividually controlling each micro LED 120.

The micro LED array MLA is disposed on the light source unit substrate110. The micro LED array MLA may include the micro LEDs 120. Here, eachof the micro LEDs 120 refers to a light emitting element having a verysmall size. In an embodiment, the size of each micro LED 120 may be 100μm or less. In some embodiments, the size of each micro LED 120 may be20 to 40 μm.

The micro LEDs 120 may be arranged in rows and columns along the firstdirection X and the second direction Y intersecting the first directionX. In an embodiment, the first direction X and the second direction Ymay perpendicularly intersect each other. Since each micro LED 120 has avery small size, at least hundreds or thousands of micro LEDs 120 may bearranged along the first direction X and the second direction Y. In anembodiment, the micro LEDs 120 may be arranged such that an averagepitch between the micro LEDs 120 is 5000 μm or less. In someembodiments, the average pitch between the micro LEDs 120 may be 20 to40 μm.

The micro LEDs 120 project light downward toward the substrate transferunit 200 or the target substrate 10. Each micro LED 120 may emit lighthaving a wavelength in a specific region. Specifically, an emissionwavelength of each micro LED 120 may include an ultraviolet region. Forexample, the emission wavelength of each micro LED 120 may be 200 to 500nm. Light emitted from each micro LED 120 may pass through the lightsource unit substrate 110 and the optical system 140 to reach the targetsubstrate 10. Each micro LED 120 may become wider toward the bottom inorder for efficient light extraction. For example, each micro LED 120may have various shapes such as a cone, a triangular pyramid, aquadrangular pyramid, a hexahedron, a quadrangular prism, and acylinder.

Each micro LED 120 may include a first semiconductor layer 121, a secondsemiconductor layer 122, an active layer 123, a first electrode 125, asecond electrode 126, a reflector 124, and a control unit circuit 127.

The first semiconductor layer 121 may be disposed on the light sourceunit substrate 110. As illustrated in FIG. 4, the first semiconductorlayer 121 of each micro LED 120 may be connected to the firstsemiconductor layer 121 of a neighboring micro LED 120. The firstsemiconductor layer 121 may be an n-type semiconductor layer.

The second semiconductor layer 122 is disposed on the active layer 123to be described later. The second semiconductor layer 122 may be ap-type semiconductor layer.

In FIG. 4, each of the first semiconductor layer 121 and the secondsemiconductor layer 122 is composed of one layer. However, each of thefirst semiconductor layer 121 and the second semiconductor layer 122 mayalso include more than one layer.

The active layer 123 is disposed between the first semiconductor layer121 and the second semiconductor layer 122. For example, the activelayer 123 may have a structure in which a semiconductor material havinga large band gap energy and a semiconductor material having a small bandgap energy are stacked on each other.

The first electrode 125 electrically connects the first semiconductorlayer 121 and a first control unit circuit 127_1 to be described later.

The second electrode 126 electrically connects the second semiconductorlayer 122 to a second control unit circuit 127_2 to be described later.

The reflector 124 has an open lower side and surrounds the firstsemiconductor layer 121, the active layer 123 and the secondsemiconductor layer 122 from the outside. The reflector 124 reflectslight generated by the active layer 123 downward.

The reflector 124 becomes wider toward the bottom so that reflectedlight is aligned in a certain direction. In an embodiment, side surfacesof the reflector 124 may be inclined at an angle of about 40 to 90degrees. In some embodiments, the side surfaces of the reflector 124 maybe inclined at an angle of about 50 degrees.

The reflector 124 may include a metal having high reflectivity or analloy of metals. For example, the reflector 124 may include aluminum(Al), gold (Au), silver (Ag), nickel (Ni), copper (Cu), rhodium (Rh),palladium (Pd), zinc (Zn), ruthenium (Ru), lanthanum (La), titanium(Ti), platinum (Pt), or an alloy of the same.

The light blocking member 130 is disposed under the light source unitsubstrate 110. The light blocking member 130 may be disposed in alattice shape to form openings corresponding to the micro LEDs 120,respectively. The light blocking member 130 may be disposed along theboundary of a unit light emitting cell LC between the micro LEDs 120.The light blocking member 130 may be made of a material that absorbs orreflects light of at least a specific wavelength band to blocktransmission of the light. The light blocking member 130 prevents mixingof light emitted from different micro LEDs 120 and reduces reflection ofexternal light. In an embodiment, the light blocking member 130 may be,for example, a black matrix made of a chromium-based metal material, acarbon-based organic material, or a resin.

The control unit circuit 127 electrically connects the light source unit100 and the control unit 300 and drives each micro LED 120 individuallyby transmitting a control signal of the control unit 300 to each microLED 120. The control unit circuit 127 may include an element and/orwiring for individually driving each micro LED 120, for example, mayinclude a data line, a scan line, a transistor, or a driver integratedcircuit. In an embodiment, the control unit circuit 127 may include thefirst control unit circuit 127_1 which electrically connects the firstelectrodes 125 and the control unit 300 and the second control unitcircuit 127_2 which electrically connects the second electrodes 126 andthe control unit 300. The first control unit circuit 127_1 and thesecond control unit circuit 127_2 are disposed parallel to each other inFIG. 4. In some embodiments, the first control unit circuit 127_1 mayapply a first power supply voltage to each micro LED 120, and the secondcontrol unit circuit 127_2 may apply a second power supply voltage.Here, the second control unit circuit 127_2 includes, for example, athin-film transistor, and the second power supply voltage isindividually applied to each micro LED 120 so that the control unit 300can drive each micro LED 120 individually.

The optical system 140 is disposed under the light source unit substrate110. The optical system 140 may guide light emitted from the micro LEDs120 in a specific direction to uniformly align the overall direction ofthe light. In some embodiments, the optical system 140 may enlarge orreduce light emitted from the micro LEDs 120.

Since the optical system 140 is integrated under the light source unitsubstrate 110 to be adjacent to the micro LED array MLA, the lightsource unit 100 may be disposed in the simple shape of bars havingrectangular shape overlapping the substrate transfer unit 200 in a planeview as illustrated in FIG. 3. That is, the exposure apparatus 1 may uselight emitting elements having a fine size and integrated with theoptical system 140. Thus, an apparatus or system for photolithographycan be miniaturized without the need for a separate optical system 140and a device for alignment and uniformization of light.

The optical system 140 may be made of a material such as glass, oxide,nitride, or sapphire. The optical system 140 may include lenses. Forexample, the optical system 140 may include a micro lens array in whichlens structures having a size of 10 to 1000 μm are arrangedtwo-dimensionally.

The micro lens array may include micro lenses having a positive ornegative curvature. In an embodiment, a width of each micro lens may beequal to or smaller than a width of each micro LED 120.

In an embodiment, each micro lens of the micro lens array may bedisposed for each micro LED 120. In some embodiments, each micro lens ofthe micro lens array may be disposed for micro LEDs 120.

The substrate transfer unit 200 transfers the loaded target substrate 10to an appropriate position for exposure. The substrate transfer unit 200may include a substrate stage 210 and a substrate stage driver 220.

The substrate stage 210 supports a lower surface of the target substrate10. The substrate stage 210 transfers the target substrate 10 in atleast one of the first, second, and third directions X, Y, and Z. In anembodiment, the substrate stage 210 transfers the target substrate 10 inthe first direction X such that at least a part of the target substrate10 disposed on the substrate stage 210 overlaps the light source unit100 in the third direction Z.

The substrate stage driver 220 moves the substrate stage 210 to transferthe target substrate 10. The substrate stage driver 220 may beelectrically connected to the control unit 300 to be described later. Inan embodiment, the substrate stage driver 220 may include a cylindricalroller connected to the substrate stage 210. The roller may rotate orstop so that at least a part of the target substrate 10 located on atransfer belt and requiring patterning is aligned under the light sourceunit 100.

The sensing unit 400 may sense whether the light source unit 100 and thetarget substrate 10 are aligned with each other so that the targetsubstrate 10 can be aligned at a correct position. In an embodiment, thesensing unit 400 may be disposed under the light source unit substrate110 to sense an alignment mark on the target substrate 10.

The control unit 300 controls at least one of the light source unit 100,the substrate transfer unit 200, and the sensing unit 400.

The control unit 300 may individually control each micro LED 120 of themicro LED array MLA to output a preset pattern. The preset pattern maybe a pattern of light generated as the amount, intensity or brightnessof light of each micro LED 120 is controlled individually. Specifically,the control unit 300 may allocate coordinates or an address to eachmicro LED 120 and transmit a control signal to each micro LED 120individually based on the coordinates or the address. In an embodiment,the control unit 300 may set an X-axis address and a Y-axis address foreach micro LED 120 and individually control each micro LED 120 bytransmitting a control signal corresponding to the set X-axis addressand Y-axis address according to the shape of the preset pattern.Accordingly, the exposure apparatus 1 can easily implement variousexposure patterns according to the shape of photoresist patterns (See‘PR_P’ in FIG. 11 and FIG. 14) to be formed on the target substrate 10without requiring a separate mask for an exposure process.

FIG. 5 illustrates an auxiliary optical system 150.

Referring to FIG. 5, an exposure apparatus 1 a may further include theauxiliary optical system 150.

The auxiliary optical system 150 may be disposed between the lightsource unit 100 and the substrate transfer unit 200 and may include atleast one lens having a positive or negative curvature. In anembodiment, the auxiliary optical system 150 may enlarge or reduce lightemitted from the light source unit 100. Accordingly, the exposureapparatus 1 a can form a more precise pattern of, e.g., 1 μm or less onthe target substrate 10 and concentrate light on a specific area of thetarget substrate 10 or disperse the light according to the lightintensity required for curing. In some embodiments, the auxiliaryoptical system 150 may align light emitted from the light source unit100 in a certain direction.

Although one auxiliary optical system 150 is illustrated in FIG. 5, morethan one auxiliary optical system 150 may also be disposed.

The operation of the control unit 300 will now be described in detailwith reference to FIGS. 6 through 14.

FIGS. 6 through 11 illustrate a method of controlling an exposureapparatus according to an embodiment of the present disclosure.

FIG. 6 is a flowchart illustrating a method of controlling an exposureapparatus according to an embodiment of the present disclosure. FIGS. 7and 8 are side views illustrating a process in which the targetsubstrate 10 is transferred and aligned. FIG. 9 illustrates a presetpattern. FIG. 10 illustrates an operation of outputting the presetpattern. FIG. 11 illustrates a developed photoresist pattern.

Referring to FIGS. 6 through 11, the method of controlling the exposureapparatus may include loading the target substrate 10 on the substratetransfer unit 200 in an operation S101, transferring the targetsubstrate 10 in an operation S102, outputting a preset pattern in anoperation S104, and transferring the target substrate 10 again in anoperation S105. The method of controlling the exposure apparatus may beperformed by the control unit 300 of the exposure apparatus 1 of FIG. 1.

The method of controlling the exposure apparatus will now be describedin detail with reference to FIGS. 7 through 11.

Referring to FIG. 7, the control unit 300 controls the substratetransfer unit 200 to transfer the target substrate 10 loaded on thesubstrate transfer unit 200 in the first direction X.

After the transferring of the target substrate 10, the method ofcontrolling the exposure apparatus may further include determiningwhether the target substrate 10 and the light source unit 100 arealigned in an operation S103.

When the target substrate 10 is located under the light source unit 100,the control unit 300 determines whether the target substrate 10 isaligned by receiving information related to the alignment from thesensing unit 400. When the target substrate 10 is not aligned, thecontrol unit 300 controls the substrate transfer unit 200 to align thetarget substrate 10 at a correct position. When the target substrate 10is aligned, the control unit 300 controls the light source unit 100 tooutput a preset pattern.

Referring to FIGS. 9 and 10, the preset pattern may be formed byindividually turning on or off at least one unit light emitting cell LCor micro LED 120 corresponding to a specific address or coordinates. Forexample, the preset pattern may be a pattern in which micro LEDs 120corresponding to (X2, Y2), (X2, Y3), (X3, Y2), (X4, Y2), (X4, Y3) and(X4, Y4) are turned off and micro LEDs 120 corresponding to the othercoordinates are turned on. The preset pattern may include patternsarranged repeatedly. The preset pattern of FIG. 9 is only an example,and the preset pattern includes all of various patterns that can be usedin a lithography process or an exposure and development process.

The control unit 300 may control the light source unit 100 to adjust theintensity or brightness of the preset pattern. Specifically, the controlunit 300 may control the light source unit 100 such that the micro LEDs120 emit light of the same intensity or different intensities. Theintensity includes brightness. In other words, the outputting of thepreset pattern may include controlling a first micro LED 120 to emitlight at a first intensity and controlling a second micro LED 120 toemit light at a second intensity. Here, the first intensity and thesecond intensity may be the same or different. In the embodiment ofFIGS. 9 and 10, the micro LEDs 120 emit light of the same intensity orbrightness. However, the output of each micro LED 120 may also becontrolled individually as in the embodiment of FIGS. 12 through 14.

Referring to FIG. 10, as each micro LED 120 is individually turned on oroff, a part of a photosensitive material PR may be exposed, and a partof the photosensitive material PR may not be exposed. As describedabove, photosensitive material PR may include photoresist. Specifically,the photosensitive material PR may be divided into exposure areas EAwhich are exposed to light as the micro LEDs 120 disposed above theexposure area EA are turned on and non-exposure areas NEA which are notexposed to light as the micro LEDs 120 disposed above the non-exposureareas NEA are turned off, e.g., not turned on.

Referring to FIG. 10, when the photosensitive material PR includes apositive photoresist, a part of the photosensitive material PR disposedin the exposure areas EA may be removed by a developer, and a part ofthe photosensitive material PR disposed in the non-exposure areas NEAmay remain to form a photoresist pattern PR_P as illustrated in FIG. 11.Then, a target material disposed on the base substrate 11 may be etchedinto a desired shape using the photoresist pattern PR_P as a mask. Aphotoresist pattern PR_P formed using a positive photoresist isillustrated in FIG. 11. In some embodiments, the photosensitive materialPR may also include a negative photoresist.

Referring again to FIGS. 7 and 8, after the outputting of the presetpattern, the method of controlling the exposure apparatus may furtherinclude determining an exposure time.

The control unit 300 may determine whether the exposure time exceeds apreset time. The exposure time refers to a period of time during whichthe target substrate 10 is exposed to the preset pattern output from thelight source unit 100.

When the exposure time is equal to or less than the preset time, thecontrol unit 300 controls the light source unit 100 to continuouslyoutput the preset pattern.

When the exposure time exceeds the preset time, the control unit 300controls the substrate transfer unit 200 to transfer the targetsubstrate 10 in the first direction X. Here, the control unit 300 maycontrol the light source unit 100 not to output the preset pattern anymore. In some embodiments, the exposure apparatus 1 may further includean additional substrate transfer unit 200 capable of transferring thetarget substrate 10 in the second direction Y or the third direction Z,and the control unit 300 may control the additional substrate transferunit 200 to transfer the target substrate 10 in a direction differentfrom the previous transfer direction.

After the target substrate 10 is moved by a sufficient distance, thecontrol unit 300 may again determine whether another area of the targetsubstrate 10 is aligned with the light source unit 100.

When the area of the target substrate 10 is aligned with the lightsource unit 100, the control unit 300 may control the light source unit100 to continuously output the same pattern to the area of the targetsubstrate 10 or to output a different pattern to the area of the targetsubstrate 10.

FIGS. 12 through 14 illustrate a method of controlling an exposureapparatus according to an embodiment of the present disclosure.

The embodiment of FIGS. 12 through 14 is different from the embodimentof FIGS. 6 through 11 in that the output of each micro LED 120 iscontrolled differently in an operation of outputting a preset pattern.

Referring to FIGS. 6 and 12 through 14, the control unit 300 may controlthe light source unit 100 such that the micro LEDs 120 emit light ofdifferent brightnesses. For example, the control unit 300 may controlthe light source unit 100 such that micro LEDs 120 corresponding to (X2,Y2), (X3, Y2), (X4, Y2), (X4, Y3) and (X4, Y4) are turned off, microLEDs 120 corresponding to (X3, Y3), (X2, Y4) and (X3, Y4) emit lighthaving a first brightness, a micro LED 120 corresponding to (X2, Y3)emits light having a second brightness, and the other micro LEDs 120emit light having a third brightness. Accordingly, a photoresist PRdisposed in each exposure area EA, e.g., EA1, EA2, EA3, may be cured toa different degree to form a stepped photoresist pattern PR_P havingvarious heights as illustrated in FIG. 14. The photoresist PR may bedivided into a non-exposure area NEA, first exposure areas EA1, a secondexposure area EA2 and third exposure area EA3. The non-exposure area NEAis an area where a micro LED 120 disposed above the non-exposure areaNEA is turned off. The first exposure areas EA1, the second exposurearea EA2 and the third exposure area EA3 are areas where micro LEDs 120disposed above the first exposure areas EA1, the second exposure areaEA2 and the third exposure area EA3 are turned on, respectively. Thelight amount or emission time of micro LEDs 120 disposed above the firstexposure areas EA1, the second exposure area EA2 and the third exposurearea may be different. For example, the light amount or emission time ofmicro LEDs 120 disposed above the second exposure areas EA2 may besmaller than the light amount or emission time of a micro LED 120disposed above the first exposure area EA1, and the light amount oremission time of micro LEDs 120 disposed above the third exposure areasEA3 may be smaller than the light amount or emission time of a micro LED120 disposed above the second exposure area EA2. That is, the exposureapparatus 1 may individually control each micro LED 120 to obtain aphotoresist pattern PR_P similar to a pattern obtained when a halftonemask is used.

The photoresist pattern PR_P of FIG. 14 is only an example.

In some embodiments, the control unit 300 may control the light sourceunit 100 to output a first preset pattern for a first preset time andoutput a second preset pattern for a second preset time. Light of themicro LEDs 120 may have the same brightness as in the embodiment ofFIGS. 9 and 10 or may have different brightnesses as in the embodimentof FIGS. 12 and 13. For example, the first preset pattern may be thepreset pattern of FIG. 9, and the second preset pattern may be thepreset pattern of FIG. 12.

A method of manufacturing a display device using the exposure apparatus1 will now be described in detail with reference to FIGS. 15 through 20.

FIGS. 15 through 20 illustrate a method of manufacturing a displaydevice according to an embodiment of the present disclosure.

The exposure apparatus 1 may be used in a process requiring complicatedpattern forming, for example, in a process of manufacturing a displaydevice. Examples of the display device may include various types ofdisplay devices such as liquid crystal displays (LCDs) and organic lightemitting displays (OLEDs). The method of manufacturing the displaydevice may be performed using the exposure apparatus 1 of FIG. 1.

FIG. 15 illustrates a method of manufacturing a display device accordingto an embodiment of the present disclosure.

Referring to FIG. 15, the method of manufacturing the display deviceincludes stacking at least one material layer on a base substrate 11 inan operation S201, coating a photosensitive material PR on the at leastone material layer in an operation S202, outputting a preset pattern byindividually controlling the amount of light of each micro LED 120 in anoperation S203, exposing the photosensitive material PR to light in anoperation S204, removing a part of the photosensitive material PR in anoperation S205, and etching a first pattern in the at least one materiallayer in an operation S206. The photosensitive material PR may include aphotoresist.

The individually controlling of the amount of light of each micro LED120 may include at least one of individually controlling on or off ofeach micro LED 120, individually controlling a driving time of eachmicro LED 120, and outputting a first preset pattern for a first presettime and outputting a second preset pattern for a second preset time.

The method of manufacturing the display device may further includeremoving a part of the remaining photosensitive material PR in anoperation S207 and etching a second pattern in the at least one materiallayer in an operation S208. Here, the at least one material layer mayinclude a first layer L1 and a second layer L2 sequentially stacked fromthe bottom, and the first pattern may be formed in the first layer L1and the second layer L2, and the second pattern may be formed in thesecond layer L2.

In FIGS. 16 through 20, a process of performing halftone etching usingthe method of manufacturing the display device of FIG. 15 isillustrated.

Referring to FIG. 16, a target substrate 10 may include a base substrate11 and a first layer L1, a second layer L2 and the photosensitivematerial PR sequentially stacked on the base substrate 11.

The first layer L1 may be composed of at least one layer. For example,the first layer L1 may include a barrier layer, a buffer layer, gateinsulating layers, an interlayer insulating film, and a semiconductorlayer, an active layer 123, an electrode, etc. for a thin-filmtransistor structure.

The second layer L2 is disposed on the first layer L1. For example, thesecond layer L2 may be a material layer for an oxide semiconductorlayer.

The photosensitive material PR is coated on the second layer L2. As thecontrol unit 300 of the exposure apparatus 1 controls the micro LEDarray MLA such that each micro LED 120 emits a different amount of lightor emits light for a different emission time, the photosensitivematerial PR may be divided into a non-exposure area NEA, first exposureareas EA1, and a second exposure area EA2. The non-exposure area NEA isan area where a micro LED 120 disposed above the non-exposure area NEAis turned off. The first exposure areas EA1 and the second exposure areaEA2 are areas where micro LEDs 120 disposed above the first exposureareas EA1 and the second exposure area EA2 are turned on. The lightamount or emission time of micro LEDs 120 disposed above the firstexposure areas EA1 may be smaller than the light amount or emission timeof a micro LED 120 disposed above the second exposure area EA2.

Referring to FIG. 17, a part of the exposed photosensitive material PRis removed by a development process. Specifically, when thephotosensitive material PR is a positive photoresist, a part of thephotosensitive material PR disposed in the non-emission area NEA mayremain intact, a part of the photosensitive material PR disposed in thefirst exposure areas EA1 may be removed, and a part of thephotosensitive material PR disposed in the second exposure area EA2 maybe completely removed. In other words, a part of the photosensitivematerial PR disposed in the non-exposure area NEA may remain to a firstheight h1, and a part of the photosensitive material PR disposed in thefirst exposure areas EA1 may remain to a second height h2 greater thanthe first height h1.

Referring to FIG. 18, parts of the first layer L1 and the second layerL2 disposed in the second exposure area EA2 may be etched using theremaining photosensitive material PR as a mask to form a first pattern.In an embodiment, the first layer L1 and the second layer L2 may beetched using different etching methods. For example, the second layer L2may be etched using a wet etching method, and the first layer L1 may beetched using a dry etching method. Depending on the degree of etching,an opening may be formed in the first layer L1, and a groove or trenchpattern may be formed in the second layer L2. The first pattern may beformed in various shapes other than the shape illustrated in FIG. 18.

Referring to FIGS. 19 and 20, a part of the remaining photosensitivematerial PR is removed by an ashing process. The remainingphotosensitive material PR disposed in the first exposure areas EA1 maybe completely removed. Accordingly, a part of the second layer L2disposed in the non-exposure area NEA may not be exposed, but a part ofthe second layer L2 disposed in the first exposure areas EA1 may beexposed. The exposed second layer L2 of the first exposure areas EA1 maybe etched again to form a second pattern.

FIGS. 21 through 24 illustrate an exposure apparatus 1 a and a method ofmanufacturing a display device using the same according to an embodimentof the present disclosure.

Referring to FIGS. 21 through 24, the exposure apparatus 1 a may also beused in a deposition process, unlike the embodiments of FIGS. 1 and 20.The deposition process may be, for example, a process of depositing anorganic material layer of an OLED.

A target substrate 10 a may be a substrate on which a deposition source32 evaporated by exposure is deposited. The target substrate 10 a mayinclude a base substrate and layers stacked on the base substrate toform thin-film transistors.

A donor substrate 30 refers to a substrate on which the depositionsource 32 is disposed. The donor substrate 30 may include a basesubstrate 31 and the deposition source 32 stacked on the base substrate31. The donor substrate 30 may include a material having high thermalconductivity, for example, a metal material.

Referring to FIG. 21, the exposure apparatus 1 a may include a lightsource unit 100, a substrate transfer unit 200 a, and a control unit300.

The light source unit 100 is disposed under the substrate transfer unit200 a. Accordingly, during deposition, the light source unit 100, thedonor substrate 30, and the target substrate 10 a may be disposed tooverlap each other sequentially from the bottom. The light source unit100 may include a light source unit substrate 110, a micro LED arrayMLA, and a light blocking member 130. The configuration and operation ofthe light source unit 100 are substantially the same or similar to thoseof the embodiments of FIGS. 1 through 19, and thus a redundantdescription of the configuration and operation of the light source unit100 will be omitted.

The substrate transfer unit 200 a transfers the donor substrate 30coated with the deposition source 32 to between the light source unit100 and the target substrate 10 a. The substrate transfer unit 200 a maytransfer the donor substrate 30 such that the donor substrate 30 isdisposed between the light source unit 100 and the target substrate 10 aduring deposition. In an embodiment, the substrate transfer unit 200 amay include rail parts supporting both edges of a lower surface of thedonor substrate 30, so that the lower surface of the donor substrate 30is sufficiently exposed to light emitted from the light source unit 100.The rail shape of FIG. 21 is only an example, and the substrate transferunit 200 a may be any transfer device that exposes the lower surface ofthe donor substrate 30 but can transfer the donor substrate 30 in atleast one of the first, second, and third directions X, Y, and Z. In anembodiment, the substrate transfer unit 200 a transfers the loaded donorsubstrate 30 in the first direction X. In some embodiments, the exposureapparatus 1 a may further include at least one of a light source movingunit which moves the light source unit 100 and a target substratetransfer unit 200 which moves the target substrate 10 a. The lightsource moving unit and the target substrate transfer unit 200 may becontrolled by the control unit 300.

The control unit 300 controls the light source unit 100 and thesubstrate transfer unit 200 a. The individual operation of each microLED 120 by the control unit 300 is substantially the same or similar tothat of the embodiments of FIGS. 1 through 20, and thus a redundantdescription of the individual operation of each micro LED 120 by thecontrol unit 300 will be omitted.

Referring to FIG. 22, the method of manufacturing the display deviceincludes transferring a first donor substrate 30_1 in an operation S301,forming a first deposition pattern on the target substrate 10 a in anoperation S302, replacing the first donor substrate 30_1 with a seconddonor substrate 30_2 in an operation S303, and forming a seconddeposition pattern on the target substrate 10 a in an operation S304.

The method of manufacturing the display device may further includedetermining whether the target substrate 10, the donor substrate 30and/or the light source unit 100 are aligned.

The method of manufacturing the display device will now be described indetail with reference to FIGS. 21 through 24.

First, the control unit 300 controls the substrate transfer unit 200 ato place the first donor substrate 30_1 at an appropriate position fordeposition. The first donor substrate 30_1 may include a firstdeposition source 32_1.

When the first donor substrate 30_1 is transferred to a position fordeposition, the control unit 300 determines whether the target substrate10 a, the first donor substrate 30_1 and/or the light source unit 100are aligned.

When determining that they are aligned, the control unit 300 controlsthe light source unit 100 to form a first deposition pattern on thetarget substrate 10 a by exposing the first donor substrate 30_1 tolight. Specifically, the control unit 300 controls the light source unit100 to output a first preset pattern. The first preset pattern may beoutput for a first exposure time. The first exposure time may be aperiod of time sufficient to form the first deposition pattern on thetarget substrate 10 a. The first preset pattern may be a pattern inwhich some of the micro LEDs 120 at predetermined intervals are turnedon as illustrated in FIG. 23.

As each micro LED 120 is individually turned on or off, the depositionsource 32 may be divided into deposition areas and non-deposition areas.The deposition areas may be areas where the micro LEDs 120 are turnedon, and the non-deposition areas may be areas where the micro LEDs 120are turned off. A part of the deposition source 32 disposed in thedeposition areas may be evaporated and deposited on the target substrate10 a, and a part of the deposition source 32 disposed in thenon-deposition areas may remain in the donor substrate 30.

When the first exposure time is equal to or greater than a first presettime, the control unit 300 may terminate the deposition process or maycontrol a transfer stage to replace the first donor substrate 30_1 withthe second donor substrate 30_2. The second donor substrate 30_2 mayinclude a second deposition source 32_2. The second deposition source32_2 may include the same material as or a different material from thefirst deposition source 32_1.

Then, the control unit 300 determines again whether the second donorsubstrate 30_2, the target substrate 10 a and the light source unit 100are aligned.

When determining that they are aligned, the control unit 300 controlsthe light source unit 100 to form a second deposition pattern on thetarget substrate 10 a by exposing the second donor substrate 30_2 tolight. Specifically, the control unit 300 controls the light source unit100 to output a second preset pattern. The second preset pattern may beoutput for a second exposure time. The second preset pattern may bedifferent from the first preset pattern. Accordingly, depositionpatterns may be formed on the target substrate 10 a such that differentmaterials do not overlap each other.

In some embodiments, unlike in FIG. 23, the second preset pattern may bethe same pattern as the first preset pattern, and deposition patternsmay be formed on the target substrate 10 a such that different materialsat least partially overlap each other.

When the second exposure time is equal to or greater than a secondpreset time, the control unit 300 may terminate the deposition processor may replace the second donor substrate 30_2 with a third donorsubstrate 30.

As each micro LED 120 is driven individually, the exposure apparatus 1 adoes not require a mask for deposition, for example, a fine metal mask(FMM) in a deposition process.

In concluding the detailed description, those skilled in the art willappreciate that many variations and modifications can be made to theembodiments without substantially departing from the principles of theinventive concept. Therefore, the disclosed embodiments of the inventiveconcept are used in a generic and descriptive sense only and not forpurposes of limitation.

What is claimed is:
 1. An exposure apparatus comprising: a light sourceunit which provides light for exposure and comprises micro lightemitting diodes arranged in a matrix form; a substrate transfer unitwhich transfers a target substrate; and a control unit which controls atleast one of the light source unit and the substrate transfer unit,wherein the control unit allocates coordinates or an address to eachmicro light emitting diode and individually controls an amount of lightof each micro light emitting diode according to a preset pattern basedon the coordinates or the address.
 2. The apparatus of claim 1, whereineach micro light emitting diode has a size of 100 μm or less.
 3. Theapparatus of claim 1, wherein an average pitch between the micro lightemitting diodes is 5000 μm or less.
 4. The apparatus of claim 1, whereinan emission wavelength of each micro light emitting diode is within arange of 200 to 500 nm.
 5. The apparatus of claim 1, wherein the lightsource unit comprises: a light source unit substrate which supports themicro light emitting diodes; and an optical system which is disposedunder the light source unit substrate.
 6. The apparatus of claim 5,wherein each micro light emitting diode comprises: a first semiconductorlayer which is disposed on the light source unit substrate; an activelayer which is disposed on the first semiconductor layer; a secondsemiconductor layer which is disposed on the active layer; and areflector which has an open lower side and surrounds the firstsemiconductor layer, the active layer and the second semiconductorlayer.
 7. The apparatus of claim 6, wherein the reflector becomes widertoward a bottom, and side surfaces of the reflector are inclined at anangle within a range of 40 to 90 degrees.
 8. The apparatus of claim 5,wherein the light source unit further comprises a light blocking memberwhich is disposed along a boundary between the micro light emittingdiodes on the light source unit substrate.
 9. The apparatus of claim 5,wherein the optical system comprises micro lenses.
 10. The apparatus ofclaim 1, wherein a distance between the light source unit and the targetsubstrate loaded on the substrate transfer unit during exposure is about500 μm or less.
 11. The apparatus of claim 1, wherein the control unitindividually controls on or off of each micro light emitting diode. 12.The apparatus of claim 1, wherein the control unit individually controlsa driving time of each micro light emitting diode.
 13. The apparatus ofclaim 1, wherein the control unit controls the light source unit tooutput a first preset pattern for a first preset time and controls thelight source unit to output a second preset pattern different from thefirst preset pattern when determining that the first preset time haselapsed.
 14. An exposure apparatus comprising: a light source unit whichprovides light for exposure and comprises unit light emitting cellsarranged in a matrix form; a substrate transfer unit which transfers atarget substrate; and a control unit which controls at least one of thelight source unit and the substrate transfer unit, wherein the controlunit allocates coordinates or an address to each unit light emittingcell and individually controls an amount of light of each unit lightemitting cell according to a preset pattern based on the coordinates orthe address.
 15. A method of manufacturing a display device, the methodcomprising: stacking at least one material layer on a base substrate;coating a photosensitive material on the at least one material layer;outputting a preset pattern by individually controlling an amount oflight of each micro light emitting diode; exposing the photosensitivematerial to light; removing a part of the photosensitive material; andetching a first pattern in the at least one material layer.
 16. Themethod of claim 15, wherein the individually controlling of the amountof light of each micro light emitting diode comprises individuallycontrolling on or off of each micro light emitting diode.
 17. The methodof claim 15, wherein the individually controlling of the amount of lightof each micro light emitting diode comprises individually controlling adriving time of each micro LED.
 18. The method of claim 15, wherein theindividually controlling of the amount of light of each micro lightemitting diode comprises outputting a first preset pattern for a firstpreset time and outputting a second preset pattern for a second presettime.
 19. The method of claim 15, further comprising removing a part ofa remaining photosensitive material.
 20. The method of claim 19, furthercomprising etching a second pattern in the at least one material layer.